Tasks Details
easy
Find the missing element in a given permutation.
Task Score
100%
Correctness
100%
Performance
100%
An array A consisting of N different integers is given. The array contains integers in the range [1..(N + 1)], which means that exactly one element is missing.
Your goal is to find that missing element.
Write a function:
class Solution { public int solution(int[] A); }
that, given an array A, returns the value of the missing element.
For example, given array A such that:
A[0] = 2 A[1] = 3 A[2] = 1 A[3] = 5the function should return 4, as it is the missing element.
Write an efficient algorithm for the following assumptions:
- N is an integer within the range [0..100,000];
- the elements of A are all distinct;
- each element of array A is an integer within the range [1..(N + 1)].
Copyright 2009–2024 by Codility Limited. All Rights Reserved. Unauthorized copying, publication or disclosure prohibited.
Solution
Programming language used C#
Total time used 4 minutes
Effective time used 4 minutes
Notes
not defined yet
Task timeline
Code: 03:43:59 UTC,
c,
verify,
result: Failed
// you can write to stdout for debugging purposes, e.g.
// printf("this is a debug message\n");
int solution(int A[], int N) {
// write your code in C# 6.0 with .NET 4.5 (Mono)
long length = A.Length;
length = (length+1)*(length+2) / 2;
for (int i = 0; i < A.Length ; i++)
{
length = length - A[i];
}
return (int)length;
}
Analysis
Compile error
func.c: In function 'solution': func.c:6:28: error: request for member 'Length' in something not a structure or union long length = A.Length; ^ func.c:8:34: error: request for member 'Length' in something not a structure or union for (int i = 0; i < A.Length ; i++) ^
Code: 03:44:14 UTC,
cs,
verify,
result: Passed
using System;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(int[] A) {
// write your code in C# 6.0 with .NET 4.5 (Mono) // write your code in C# 6.0 with .NET 4.5 (Mono)
long length = A.Length;
length = (length+1)*(length+2) / 2;
for (int i = 0; i < A.Length ; i++)
{
length = length - A[i];
}
return (int)length;
}
}
Analysis
Code: 03:44:19 UTC,
cs,
verify,
result: Passed
using System;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(int[] A) {
// write your code in C# 6.0 with .NET 4.5 (Mono) // write your code in C# 6.0 with .NET 4.5 (Mono)
long length = A.Length;
length = (length+1)*(length+2) / 2;
for (int i = 0; i < A.Length ; i++)
{
length = length - A[i];
}
return (int)length;
}
}
Analysis
Code: 03:44:27 UTC,
cs,
verify,
result: Passed
using System;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(int[] A) {
// write your code in C# 6.0 with .NET 4.5 (Mono) // write your code in C# 6.0 with .NET 4.5 (Mono)
long length = A.Length;
length = (length+1)*(length+2) / 2;
for (int i = 0; i < A.Length ; i++)
{
length = length - A[i];
}
return (int)length;
}
}
Analysis
Code: 03:44:30 UTC,
cs,
final,
score: 
100
using System;
// you can also use other imports, for example:
// using System.Collections.Generic;
// you can write to stdout for debugging purposes, e.g.
// Console.WriteLine("this is a debug message");
class Solution {
public int solution(int[] A) {
// write your code in C# 6.0 with .NET 4.5 (Mono) // write your code in C# 6.0 with .NET 4.5 (Mono)
long length = A.Length;
length = (length+1)*(length+2) / 2;
for (int i = 0; i < A.Length ; i++)
{
length = length - A[i];
}
return (int)length;
}
}
Analysis summary
The solution obtained perfect score.
Analysis
Detected time complexity:
O(N) or O(N * log(N))
expand all
Correctness tests
1.
0.060 s
OK
2.
0.061 s
OK
1.
0.061 s
OK
2.
0.061 s
OK
1.
0.060 s
OK
2.
0.061 s
OK
1.
0.060 s
OK
2.
0.061 s
OK
3.
0.061 s
OK
1.
0.061 s
OK
expand all
Performance tests
1.
0.064 s
OK
1.
0.064 s
OK
1.
0.095 s
OK
2.
0.078 s
OK
3.
0.077 s
OK
1.
0.096 s
OK
1.
0.081 s
OK